1. Field of the Invention
The present invention relates to a wiring board having a mounting region for a memory and an electronic device on which the wiring board is mounted.
2. Prior Art
Main circuit parts such as processors (CPU or the like), a main memory, and the like constituting an electronic device such as a computer are mounted on a basic circuit board (wiring board) called a mother board, and the basic circuit board is accommodated in the main body of the electronic device.
The main memory is a RAM (DRAM chip) mainly used as a work area of the CPU, is mounted on a mounting portion (called a xe2x80x9cpadxe2x80x9d), formed on a mother board, for the main memory, and is electrically connected to another circuit through wires connected to the pad.
When an electronic device is to be manufactured, a main memory having a specification (configuration or the like of a storage element constituting a storage capacity and a main memory bank) selected by a maker or a vender such as a seller is mounted on a mother board. On the mother board, necessary electronic circuit parts are mounted. Thereafter, the mother board on which the necessary parts are mounted is mounted on the main body of the electronic device. When the electronic device is in a state in which the electronic device can be shipped, the electronic device is shipped.
As described above, a main memory having a specific specification selected by a vender is mounted (soldered) on the mother board until the electronic device is shipped. A user can expand the work area of the CPU by adding an expanded memory after the electronic device is purchased. For this reason, it is not expected that the main memory is exchanged after the electronic device is purchased by the user.
For this reason, wires (including pads) for a main memory of a mother board are formed such that only a specific main memory can be mounted. More specifically, a main memory has only one specification corresponding to one type of mother board.
With a great variety of computer systems in recent years, users require a great variety of specifications of electronic devices such as computers, and the demands of the users extent to the storage capacities of main memories mounted in a shipping state. For example, a user who wants to make the processing speed of a CPU as high as possible desires that a main memory having a capacity which is as large as possible is mounted. On the other hand, a user who wants to, even slightly, suppress the price of an electronic device desires a reduction in price of the electronic device in place of a reduction in storage capacity of the main memory.
However, only a main memory can mounted on a conventional mother board. For this reason, the conventional mother board can respond to the demand of a user. In addition, if the specification of the main memory is changed in response to the demand of a user, mother boards must be prepared for the specifications of main memories, respectively. High costs and long time are required.
It is an object of the present invention to provide a wiring board being capable of supplying an electronic device depending on a demand of a user by making it possible to select the storage capacity of a memory mounted before shipment and an electronic device comprising the wiring board.
The first aspect of the present invention is a wiring board including a mounting region in which memories having different storage capacities can be mounted. The mounting region has: first wires for, when a first memory is mounted, making it possible to access all the addresses of the first memory; and second wires for, when a second memory having a storage capacity different from that of the first memory, making it possible to access to all the addresses of the second memory.
According to the first aspect of the present invention, one of the first memory and the second memory can be mounted in the mounting region. For this reason, the total capacity of the memory mounted in the mounting region, i.e., the total capacity of the main memory can be changed. Therefore, the total capacity of the main memory can be selected depending on a demand of a user.
The memory mounted in the mounting region is a main memory (to be referred to as an internal memory, an internal RAM, a system RAM, or the like) which is mounted before an electronic device having the wiring board of the present invention mounted thereon is shipped by a vender and which is not expected to be exchanged. The memory does not include an expanded memory (expanded RAM) added by a user or the like after the electronic device having the wiring board mounted thereon is shipped. The wiring board of the present invention has a plurality of mounting regions, and at least one of the plurality of mounting regions or all the plurality of mounting regions may have the configurations described above.
In the first aspect, the mounting regions may be formed on both the surfaces of the wiring board. In this manner, the spaces on the wiring board can be effectively used.
In the first aspect, the first memory may be constituted by a plurality of storage elements, and the first wires may be electrically connected to the storage elements constituting the first memory, the second memory may be constituted by a plurality of storage elements, having the same bit configurations as those of the storage elements constituting the first memory, the number of which is equal to that of the storage elements of the first memory, and the second wires may be electrically connected to the storage elements constituting the second memory.
In the first aspect, the first wires and the second wires may have portions which are commonly used for the first memory and the second memory.
The second aspect of the present invention is an electronic device including a wiring board. This wiring board includes a mounting region in which memories having different storage capacities can be mounted. The mounting region has: first wires for, when a first memory is mounted, making it possible to access all the addresses of the first memory; and second wires for, when a second memory having a storage capacity different from that of the first memory, making it possible to access to all the addresses of the second memory.
An electronic device has a wiring board on which a memory conforming to the definition described above is mounted, and is a personal computer, a work station, a mobile computer, or the like.
According to the wiring board according to the present invention and the electronic device including the wiring board, the storage capacity of a memory mounted before shipment can be selected. An electronic device depending on a demand of a user can be supplied to the user.